1. Field of the Invention
The present invention generally relates to a robotic system for positioning rows of sliders and a method for dicing the slider rows. More particularly, the invention concerns an apparatus, method, and article of manufacture for positioning and dicing the slider rows based upon a positional relationship of a slider's ABS centroid.
2. Description of the Related Art
In the manufacture of magnetresistive transducers used to retrieve data from direct access storage devices, the term slider is used to describe a unit that carries one or more magnetic heads and positions them for transduction with a disk surface in a disk drive. The slider is mounted in a head/gimble assembly (HGA) held at one end of a suspension system, and used for positioning the magnetic head. It is critical to the operation of the head that overall tolerances for the suspension system be maintained within predetermined limits.
Responsive to the drive toward reducing manufacturing costs, batch fabrication processes have been developed for efficient, high volume production of miniaturized magnetic heads on sliders. First, heads are manufactured, using well-known monolithic methods, on a substrate of slider material. Heads are typically constructed in multiples on the substrate. The substrate is then repeatedly sliced in order to separate individual sliders from the surrounding sliders. The substrate is first parted into rows, each row containing numerous sliders arranged in a single column fashion. Individual sliders are then parted from the slider row, with the parting defining a parting surface on the slider. To further increase efficiency, it is common for several sliders to be parted from several slider rows at one time using gang wheel parting.
Various gang wheel parting techniques are well known to those skilled in the art. Gang wheel parting technology reduces the number of passes that a parting machine must make across a row to separate the individual sliders. Unfortunately, a certain degree of precision is sacrificed when using gang wheel parting techniques. The precision with which individual sliders can be parted from a row using gang parting is limited by the cutting wheels used, the precision of the cutting machine, the use of wheel gangs to increase productivity, and fixture tolerances. Nonlinear wear characteristics of the cutting wheels performing the separation process, and the cumulative tolerance error caused by the cutting machine, gang wheels, and the fixtures, have pushed currently known parting systems to their limits for maintaining tolerance levels.
Commonly, slider manufacturing costs are reduced by increasing slider row fabrication densities. By increasing row densities, head manufacturing production can increase without facility expansion, and construction of a row uses substantially the same amount of resources. This equates to more product at the same expense. Increased slider row densities allow more sliders to be manufactured in a given slider row, but require very small parting lines between individual sliders. A recent high density slider manufacturing technology developed by the assignee corporation, for example, permits a maximum parting kerf of only 0.065 mm.
A major problem arises in assembling small sliders into head gimbal assemblies. One such problem concerns fly height performance. To achieve roll static attitude requirements for HGAs with very small sliders, the alignment of the slider ABS (air bearing surface) centroid to the suspension load point must be maintained to tighter tolerances than is possible using current parting techniques. The alignment of the ABS centroid to slider body for current slider designs available from the assignee corporation requires a tolerance as small as +/-10.0 .mu.m, as measured from the parting surface of a slider body to the ABS centroid. Unfortunately, current technology is only capable of maintaining a tolerance of approximately +/-40 .mu.m between the air bearing surface (ABS) centroid of a slider and the parting cut, and holding tighter tolerances using this batch fabrication regime is not currently possible.
One attempt to overcome the limitations of the current parting system limitations has been to improve the overall tolerance of the suspension assembly to which the slider is coupled. But due to the complexity of the typical suspension system, improving a suspension's cumulative tolerance adds prohibitive costs to the suspension assembly.
Accordingly, in order to maintain an ABS-centroid-to-parting-surface tolerance as required for state of the art sliders, new methods and machines for parting sliders from a slider row are needed.